The present invention relates to a cooling system for cooling a component which is movable relative to a stationary component, such as a rotor which is rotatably seated in a stationary device. In devices having stationary components as well as components relatively movable with respect to the stationary components, such as a computer tomograph, dissipating heat generated by the operation of the device must be undertaken at a location which does not disturb the intended operation of the device. In units such as computer tomography devices, a source of such heat is the leakage heat of the radiation detector and/or of the measuring electronics, which must be dissipated. Oil circulation can be provided for this purpose, with the cooling oil circulating between the components to be cooled and an oil cooler wherein the temperature of the oil is lowered, for example, by a ventilator. A problem is that the oil cooler in such an arrangement must be disposed on the movable part, i.e. the rotor, thereby causing substantial heating in the interior of the computer tomograph. Another problem is that localized heating, or heat pockets, may form. The sensitive measuring electronics are thus subjected to heat which can falsify readings and shorten the lifetime of the electronics.